Typical electrophysiology (EP) catheters have limited steering possibilities, and can usually only be bent in one direction transverse to the extent of the distal end of the catheter. Using this bending in combination with twisting or rolling the catheter to adjust a roll angle and thereby the direction of the bending, are the manoeuvres the operator uses to steer the catheter through the patient anatomy. It is therefore of importance for the operator to control the roll angle in relation to the patient anatomy, as this is needed to be able to bend the catheter tip in the right direction.
Steering catheters in patients is sometimes performed under guidance of a medical imaging modality, e.g. magnetic resonance imaging (MRI), but even this does not allow the operator to directly determine the catheter roll angle in relation to patient anatomy. Bending of the tip while monitoring it may give some indication, but this will only be conclusive for roll angles where the bending is transverse to the direction of imaging (i.e. in the image plane).
It is thereby a disadvantage that roll angle information is not directly available to the operator of EP catheters. Hence, an improved catheter system which could provide roll angle information would be advantageous.
Another problem when EP catheters are used in MRI environments is the presence of artefacts on the measured EP signal caused by the MR system. The switched gradient fields induce signal artefacts which contain similar frequencies as the physiological EP signal. Filtering these signals to reduce artefacts based on the gradient signal from the MRI apparatus is troublesome, as extracting and scaling an electrical signal proportional to the induced artefact is not simple. A data connection to the MR scanner has to be established and the retrieved gradient waveform has to be sampled and filtered in the same way as the EP signal. Furthermore, the relation of the gradient waveform to the actual artefact is often ambiguous.
It is thereby a disadvantage that gradient induced artefacts on signal measured by EP catheters in MRI environments cannot be efficiently filtered. Hence, an improved catheter system with improved electric signal filtering capabilities would be advantageous.
U.S. Pat. No. 5,788,692 discloses an EP catheter with ring electrodes that are segmented into separate electrode segments for the purpose of improving the spatial resolution of the acquired electrophysiology signals.